A wireless network architecture of a current evolved packet system (EPS) is shown in FIG. 1, in which functions of main network entities are as follows:
An evolved universal terrestrial radio access network (E-UTRAN) is a network including a plurality of base stations (Evolved Node B, eNodeB, or eNB), and implements a wireless physical layer function, and functions of resource scheduling and wireless resource management, wireless access control, and mobility management. An eNodeB is connected to an S-GW by using a user plane interface S1-U, to transfer user data, and is connected to an MME by using a control plane interface S1-MME, to implement functions, such as radio access bearer control, by using the S1-AP protocol.
The mobility management entity (MME) is mainly responsible for all control plane functions of user session management, which include non-access-stratum (NAS) signaling and security management, tracking area list management, selection of a P-GW and an S-GW, and the like.
The serving gateway (S-GW or SGW) is mainly responsible for data transmission, data forwarding, and route switching of user equipment (UE), and serves as a local mobility anchor point when the user equipment is handed over between eNodeBs. For each user equipment, only one S-GW serves the user equipment at each moment.
A PDN gateway P-GW, or PGW) serves as an anchor point for connecting to a packet data network (PDN), and is responsible for allocation of an IP address to the user equipment, filtration of a data packet for the user equipment, rate control, charging information generation, and the like.
The user equipment accesses the EPS network and establishes a PDN connection by using an attach procedure. In this process, the PGW allocates a PDN address to the user equipment, and the user equipment is connected to the PGW by using the PDN address and implements data transmission with an external network by using the PGW. After the attach procedure ends, the UE may apply for an extra PDN connection to obtain an extra PDN address, and a specific procedure is similar to the attach procedure.
In order to solve a bottleneck problem in air interface transmission, it is expected by people that a dual connectivity feature can be used by the UE, so as to increase a rate of transmission between the UE and a base station. That is, the UE is connected to two eNBs at the same time, and a plurality of bearers is transmitted on the different eNBs. However, in a conventional bearer process, there is no special control on dual connectivity. When a first eNB transfers some bearers of the UE to a second eNB, because a corresponding network side device does not know a dual connectivity process thereof, a conventional manner for processing a single-connection bearer is still used. Obviously, such a manner for processing a single connection cannot satisfy a dual-connectivity processing requirement when it is applied to dual-connectivity bearers, thereby leading to communication abnormality.